Abstract
Synthetic strelkinite Na[(UO2)(VO4)] · nH2O (n = 0, 1, 2) was systematically investigated by single crystal X-ray diffraction and thermoanalytical methods. The anhydrous form and two hydrates were isolated as single crystals and the structures of these phases solved: Na[(UO2)(VO4)], monoclinic, P21/c, a = 6.0205(1) Å, b = 8.3365(1) Å, c = 10.4164(2) Å, β = 100.466(2)°, V = 514.10(1) Å3, R1 = 0.0337; Na[(UO2)(VO4)] · H2O, monoclinic, P21/c, a = 7.722(2) Å, b = 8.512(1) Å, c = 10.480(4) Å, β = 113.18(3)°, V = 633.3(3) Å3, R1 = 0.1658; Na[(UO2)(VO4)] · 2 H2O, monoclinic, P21/n, a = 16.2399(5) Å, b = 8.2844(2) Å, c = 10.5011(2) Å, β = 97.644(2)°, V = 1400.24(6) Å3, R1 = 0.0776. A possible mechanism of the structural transformation processes during dehydration is proposed based on the structures of the anhydrous phase and the hydrates.
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